CARBONYLATION PROCESS

Abstract: The invention provides a process for the carbonylation of ethylenically unsaturated compounds by reaction with carbon monoxide and a co-reactant in the presence of a substantially non-acidic catalyst system based on a palladium compound and a bidentate ligand of the formula (I): R<1>R<2>M<1>RM<2>R<3>R<4> wherein M<1> and M<2> independently represent a phosphorus, arsenic or antimony atom, R represents a bivalent organic bridging group, R<1>, R<2>, R<3> and R<4> independently represent substituted or non-substituted aliphatic groups, with the proviso that R<1> together with R<2>, and/or R<3> together with R<4> represent a bivalent cyclic group with at least 5 ring atoms whereby the two free valencies are linked to M<1> or M<2>, respectively. In addition, the invention provides catalytic compositions comprising: a) a palladium compound; b) a bidentate ligand of the formula (II): R<1>R<2>PRPR<3>R<4> wherein R is a bivalent organic bridging group containing from 1 to 10 atoms in the bridge and R<1>, R<2>, R<3> and R<4> independently represented substituted or non-substituted aliphatic groups, with the proviso that R<1> together with R<2> and/or R<3> together with R<4> represent a bivalent cyclic group with at least 6 ring atoms whereby the two free valencies are linked to the phosphorus atoms(s) and c) a basic compound.

Description: CARBONYLATION PROCESS The invention relates to a process for the carbonylation of ethylenically unsaturated compounds by reaction with carbon monox¬ ide and a co-reactant in the presence of a palladium-containing catalyst system. Various carbonylation reactions of this type are disclosed in EP-A-0,495 , 547. In the process described in that document, an optionally substituted olefinically unsaturated compound is reacted with carbon monoxide and a variety of co-reactants in the presence of a catalyst system comprising: a source of palladium cations; a source of bidentate ligands; and a source of anions, wherein the ligands are selected from diphosphines having the general formula 1 2 3 4 1 2 3 4 Q Q PXPQ Q , wherein the groups Q , Q , Q , and Q independently represent an optionally substituted aliphatic group, or Q together 2 3 4 with Q , and/or Q together with Q , represent an optionally substituted bivalent aliphatic group, and X represents a bivalent bridging group containing from 1 to 10 atoms in the bridge. As anion source, preferably a protonic acid is selected. Preference is in particular given to sources of non- or weakly-coordinating anions, i.e. anions which do not or only weakly coordinate with the palladium cation. Whilst the process disclosed in EP-A-0 ,495 , 547 in general provides the desired product in good yield and with high selectivi¬ ty, it has been experienced that the reaction rate in some instanc¬ es leaves room for improvement. Efforts have therefore continued to achieve an increase in reaction rate, without impeding other factors such as selectivity or catalyst stability. Surprisingly it has now been found, that by using a substan¬ tially non-acidic catalyst system and by selecting a specific category of bidentate ligands, the rate of a number of carbonyl- ation reactions is significantly increased. The invention may be defined as relating to a process for the carbonylation of ethylenicallv unsaturated compounds by reaction with carbon monoxide and a co-reactant in the presence of a sub¬ stantially non-acidic catalyst system based on a palladium compound and a bidentate ligand of the formula R 1 R 2 M 1 RM 2 R 3 R 4 (I) 1 2 wherein M and M independently represents a phosphorus , arsenic or antimony atom, R represents a bivalent organic bridging group, R , 2 3 4 R , R and R independently represent substituted or non-substitut- 1 2 ed aliphatic groups, with the proviso that R together with R , 3 4 and/or R together with R represent a bivalent cyclic group with at least 5 ring atoms whereby the two free valencies are linked to 1 2 M or M , respectively. It is believed that the carbonylation reactions ' according to the invention proceed under the influence of an active catalyst system containing palladium cations, in complex coordination with a bidentate ligand. The palladium cations may originate from salts, for example salts derived from nitric acid, sulphuric acid, and sulphonic acids, such as p-toluenesulphonic acid, methanesulphonic acid or trifluoromethanesulphonic acid. Preferably, a palladium salt of a carboxylic acid is used, for example acetic acid, trifluoroacetic acid or propionic acid. If desired, the metallic element or a zero valent palladium complex, e.g. with carbon monoxide can be used. However, this will require the presence of a protonic acid and it will be appreciated that the amount thereof has to be selected very carefully, in order to avoid that an acidic catalyst system re¬ sults . 1 2 In the bidentate ligands of formula (I) , both M and M preferably represent phosphorus atoms . R preferably represents a bivalent organic bridging group, containing from 1 to 10 atoms in the bridge. More preferably, R represents an alkylene group con¬ taining from 1 to 4 atoms in the bridge. In general the bridging group consists of carbon and hydrogen atoms only, but it may also comprise a carbon chain, interrupted by a heteroatom, such as an oxygen atom. In particular preferred are ligands of formula (I) in which R represents an ethylene group. 1 ~ 3 The cyclic group(s) formed by R together with R , and/or R together with R comprise at least 5 ring atoms, in particular from 6 to 9 ring atoms. As a rule they comprise only carbon atoms as ring atoms, but cyclic groups containing 1 or 2 heteroatoms in the ring, such as oxygen- or nitrogen-ring atoms are not precluded. Very suitable are bivalent cyclic groups, whereby the ring consists of 7 or, preferably, 8 carbon atoms. The two free valencies may occur at adjacent carbon ring atoms, or at two carbon atoms which are further apart. Examples of suitable cyclic groups are: 1 , 2-cyclooctylene , 1 , 3-cyclooctylene , 1 ,4-cyclooctylene , 1,5-cyclo- octylene , 1 ,4-cyclohexylene , 1 , 3-cycloheptylene and 1,4-cvclo- heptylene groups. Mixtures of bidentate ligands may be used as well, whereby R together with R represent various cyclic groups 3 4 3 and R and R represent either non-cyclic aliphatic groups or R , 4 together with R represent cyclic groups which may be the same as 1 2 or different from the cyclic group represented by R and R . Examples of suitable bidentate ligands selected from the [4.2.1] and/or [3.3.1] isomers of 1 , 2-bis(9-phosphabicyclononyl)ethane and 1, 2-bis(9-phosphabicyclononyl)propane ; 1 , 3-bis(9-phosphabicyclo- [3.3.1. ]nonyl)propane and 1 , 3-bis(9-phosphabicyclononyl)propane ; and " l-dialkylphosphino-2-P- (9-phosphabicyclononyl)ethane . If R and 2 3 4 R , or R and R do not represent a bivalent cyclic group, they suitably represent an optionally substituted alkyl , preferably a C, r alkyl, or monovalent cycloalkyl, preferably a cyclo C 1-6 5-lu alkyl group. Examples of suitable alkyl groups are methyl, ethyl or butyl groups. Suitable cycloalkyl groups are for example cyclohexyl or cyclooctyl groups . The ratio of number of moles of ligands of formula (I) per gram atom of palladium is preferably in the range of from 0.5 to 10, most preferably in the range of from 1 to 3. The process according to the invention is preferably carried out in the presence of a basic compound. It is believed that the presence of a basic compound not only ensures that the catalyst system remains non-acidic during the process, but also favourably affects the catalytic activity. Accordingly, it is considered likely, that at least part of the quantity of basic compound participates in the catalyst system. Suitable basic compounds, in particular, are nitrogen bases, preferably nitrogen-containing compounds wherein the nitrogen atom(s) is (are) only linked to atoms, other than hydrogen. Examples of suitable nitrogen bases are trialkylamines , preferably tri-C alkyl-amines , especially triethylamine , tripropylamine , tri-n-butylamine and tri-tert.butyl- 0 amine . Examples of suitable cyclic amines are pyridine and alkyl- pyridines , e.g. (C alkyl)pyridines , such as 2-methylpyridine , 3 ,4-dimethylpyridine and 1 , 10-phenanthroline . The amount of basic compound is not critical and may vary between wide limits. Usually a molar amount of basic compound is selected in the range of from 1 1 to 100, preferably in the range of from 1 to 20, per gram atom of palladium. Conveniently, the amount of catalyst system is relative¬ ly small. Preferred amounts are in the range of 10 to 10 gram atom palladium per mole of ethylenically unsaturated compound, more - fx - 9 preferably in the range of 10 to 10 on the same basis. Catalyst compositions comprising: a) a palladium compound; b) a bidentate ligand of the formula 1 2 3 4 R R PRPR R (II) wherein R is a bivalent organic bridging group containing from 1 to ?ς 1 2 3 4 ^ J 10 atoms in the bridge and R , R , R and R independently repre¬ sent substituted or non-substituted aliphatic groups, with the 1 2 3 4 proviso that R together with R and/or R together with R repre¬ sent a bivalent cyclic group with at least 6 ring atoms, whereby the two free valencies are linked to the phosphorus atom(s) ; and 30 c) a basic compound, are novel. Accordingly, the invention also relates to these novel cata¬ lyst compositions. The invention in particular relates to catalyst compositions comprising: a palladium compound; a bidentate ligand r n 3 -ι •3 - > of formula (II). wherein R R P and R R P each represent the [4.2.1] and/or [3.3.1] isomer of a 9-phosphabicyclononyl group and R represents an ethylene group; and pyridine or a trialkylamin . The bidentate ligands of formula (II) mav be prepared by known techniques such as those described in British Patent Specification No. 1,127,965. The ethylenically unsaturated compound may have one or more double bonds. It is preferably an olefin having from 2 to 20 carbon atoms per molecule. The unsaturated bond(s) may be internal or, preferably, terminal. In particular preferred are olefins having from 2 to 8 carbon atoms per molecule, such as ethene, propene, butene-1, hexene-1 and octene-1. In the ethylenically unsaturated compound one or more hydrogen atoms may have been substituted by other atoms, such as halogen atoms or by groups of atoms , such as hydroxyl groups , cyano groups . such as methoxy or ethoxy groups, or amino groups such as dimethyl- and diethyl-amino groups. Another preferred category of ethylenically unsaturated compounds, consists of unsaturated esters of carboxylic acids and esters of unsaturated carboxylic acids. For example, the starting material may be a vinyl ester of a carboxylic acid such as acetic acid or propionic acid, or it may be an alkyl ester of an unsatu¬ rated acid, such as the methyl or ethyl ester of acrylic acid or methacrylic acid. Suitable co-reactants in the process of the invention include compounds comprising a nucleophilic moiety and a mobile hydrogen atom. Examples are mono- and dihydric alkanols, such as methanol, ethanol, n-butanol, ethylene glycol, isopropanol , butanediols and hexanol-1, and amines, such as ethylamine and diethylamine . Alka¬ nols with 1 to 6 carbon atoms per molecule and alkanediols with 2 to 6 carbon atoms per molecule are preferred. n-Butanol-l, methanol and 1,4-butanediol are especially preferred. The use of these compounds as co-reactants enables the production of valuable carbonylation products, such as methylpropionate , butylpropionate and 1 ,4-diacyloxy butanes. These compounds are of commercial interest and mav be used as solvents and in flavouring compositions and perfumes. In the process of the invention the ethylenically unsaturated compound, or the co-reactant may be used in excess and, accordingly, may serve as solvent during the reaction. It is also possible to perform the reaction in the presence of an additional liquid diluent, in particular when the reactants are used in stoichiometric amounts. Suitable diluents are for example polar, aprotic compounds, such as ketones or ethers. Preferred diluents are tetrahydrofuran and the dimethylether of diethyleneglycol (diglyme) . If so desired, the reaction may be performed in the further- presence of a promoter, such as a drying agent. Suitable drying agents include acetals, such as dimethyl-acetal of acetone, ketals and the like. A preferred drying agent is trimethyl orthoformate . The carbonylation reaction is conveniently carried out at moderate temperatures, generally being in the range of from 30 to 200 °C, preferably in the range of from 50 to 150 °C. Reaction pressures may be atmospheric or superatmospheric . In particular pressures in the range of from 5 to 70 bar are preferred. Higher pressures are not precluded, but usually do not provide advantages. The invention will be illustrated by the following examples. Examples I-XI The experiments were carried out by each time charging a 250 mL magnetically-stirred "Hastelloy C" (trade mark) autoclave with 0.25 mmol palladium(II)acetate , 0.6 mmol of a diphosphine ligand, 50 mL of an alkanol co-reactant and, where applicable, one or more additives. The autoclave was flushed with a 1.5:1 molar mixture of carbon monoxide and ethene and pressurized to a total pressure of 50 bar. The autoclave was then sealed and the mixture was heated to the desired reaction temperature. The reaction was continued to complete ethene conversion and subsequently the reaction mixture was cooled to room temperature and the pressure released. The ligand, co-reactant, additive (if any), reaction temperature and average hourly rate of ester formation are shown in Table 1. The abbreviations used in the table have the following meanings : BPBNP = 1 , 3-bi (9-phospha-bicyclononyl)propane MBPBNE = 1 -methyl- 1 , 2-bis(9-phospha-bicyclononyl )ethane 1 , 2-bis(9-phosphabicyclononyl)propane BPBNE = 1 , 2-bis(9-phospha-bicyclononyl)ethane DMP = 3 ,4-dimethylpyridine(lutidine) Phen = 1 , 10-phenanthroline BBA = 2 , 6-di(sec .butoxy)benzoic acid TEA = triethvlamine TMF = trimethyl orthoformate The product obtained in Example V was methylpropionate ; in the other examples n-butylpropionate was obtained. The selectivity with respect to the ester was more than 99%. From the results of Exam- pies I, II and III it can be seen that by the presence of a basic compound, the rate is increased and that a further increase in rate is obtained by adding a drying agent. Likewise, comparing the results of Examples IV, VI, VII and VIII, an increase in rate is observed by adding a drying agent or a basic compound. The effect of adding a drying agent is further illustrated by comparing the results of Examples IX and X. Example B (not according to the invention, for comparison only) An experiment was carried out, substantially under the condi¬ tions as described for Example IV with the differences that the reaction tempe.rature was 130 °C, instead of 125 °C and that as ligand 1,2-bis(dicyclohexylphosphino)ethane was used. The rate was 30 mol/gat Pd.h. Example C (not according to the invention, for comparison only) An experiment was carried out, substantially under the condi¬ tions as described for Example II, with the difference that as ligand 1 , 3-bis(di-sec .butylphosphino)propane was used. The rate was 50 mol/gat Pd.h. Table 1 Example Ligand Addit ive Alkanol Temperature Rate (mmol) ( L) ( °C) (mol/gat Pd.h) I BPBNP - n-butanol 50 125 35 II DMP 10 137 85 III 137 330 TMF 5 mL IV BPBNE - 125 520 V - methanol 50 125 490 VI TMF 1 mL n-butanol 50 125 600 VII Phen 1 125 630 VIII Phen 2.5 π 125 1150 TMF 1 mL A* BBA 10 120 360 IX TEA 10 133 275 X 133 725 TMF 5 mL XI " DMP 10 " 135 1160 TMF 5 mL * not according to the invention, for comparison only Example XII An experiment was carried out, whereby the autoclave (magneti¬ cally stirred, 250 mL, "Hastelloy C") was charged with 0.25 mmol palladium (II) acetate, 0.6 mmol of a diphosphine ligand (BPBNP as defined above), 10 mmol of triethylamine, 5 mL of trimethyl ortho- formate, 50 mL of methanol and 20 mL of n-octene-1. The autoclave was flushed and pressurized with carbon monoxide to a pressure of 30 bar. The mixture was heated to 130 °C. The reaction was contin¬ ued to complete octene conversion and subsequently the reaction mixture was cooled to room temperature and the pressure released. The rate was 100 mol/gat Pd.h. The linearity of the formed methyl ester of nonanoic acid was 73%. Example XIII An experiment was carried out, substantially as described in Example XII, with the difference that instead of BPBNP as ligand BPBNE was used. (BPBNP and BPBNE are as defined above). The rate was 170 mol/gat Pd.h. The linearity of the formed methyl ester of nonanoic acid was 69%. Example XIV An experiment was carried out, substantially as described in Example I, with the difference that 40 instead 50 mL n-butanol was used, at a temperature of 130 °C and using MBPBNE instead of BPBNP as ligand. (BPBNP and MBPBNE are as defined above). The rate was 200 mol/gat Pd.h. The selectivity with respect to n-butylpropionate was more than 99%.

Claims: C L I M S 1. A process for the carbonylation of ethylenically unsaturated compounds by reaction with carbon monoxide and a co-reactant in the presence of a substantially non-acidic catalyst system based on a palladium compound and a bidentate ligand of the formula R 1 R 2 M 1 RM 2 R 3 R 4 (I) 1 2 wherein M and M independently represent a phosphorus, arsenic or antimony atom, R represents a bivalent organic bridging group, R , 2 3 4 R , R and R independently represent substituted or non-substitut- 1 2 ed aliphatic groups, with the proviso that R together with R . 3 4 and/or R together with R represent a bivalent cyclic group with at least 5 ring atoms whereby the two free valencies are linked to 1 2 M or M , respectively. 1 2 2. A process as claimed in claim 1, wherein M and M both represent phosphorus atom . 3. A process as claimed in claim 1 or 2 , wherein R represents a bivalent organic bridging group containing from 1 to 10 atoms in the bridge . 4. A process as claimed in any one of claims 1 to 3 , wherein R represents an ethylene group. 5. A process as claimed in any one of claims 1 to 4 , wherein the 1 2 bivalent cyclic group represented by R together with R , and/or by 3 ' 4 R together with R , is a cycloalkylene group having from 6 to 9 ring atoms . 6. A process as claimed in claim 5, wherein R is linked to two phosphorus atoms, each of which participates in the [4.2.1] and/or [3.3.1] isomer of a 9-phosphabicyclononyl group. 7. A process as claimed in any one of claims 1 to 6 , wherein the reaction is carried out in the presence of a basic compound. 8. A process as claimed in claim 7, wherein as basic compound pyridine, a substituted pyridine or a trialkylamine is used. 9. A process as claimed in any one of claims 1 to . wherein the reaction is carried out in the presence of a liquid diluent. 10. A process as claimed in claim 9, wherein as diluent an ether is used, in particular tetrahydrofuran or the dimethvlether of diethylene glycol. 11. Catalyst composition comprising: a) a palladium compound; b) a bidentate ligand of the formula 1 2 3 4 R R PRPR R (II) wherein R is a bivalent organic bridging group containing from 1 to 1 2 3 4 10 atoms in the bridge and R , R~ , R and R independently repre¬ sent substituted or non-substituted aliphatic groups, with the 1 2 3 4 proviso that R together with R and/or R together with R repre¬ sent a bivalent cyclic group with at least 6 ring atoms whereby the two free valencies are linked to the phosphorus atom(s) and c) a basic compound. 1 2 12. Catalyst composition as claimed in claim 11, wherein R R P and 3 4 R R P each represent the [4.2.1] and/or [3.3.1] isomer of a 9-phosphabicyclononyl group and wherein the basic compound is pyridine, a substituted pyridine or a trialkylamine .

Inventors: DRENT EIT, HASSELAAR MELIS, PELLO DENNIS HUMPHREY LOUIS, DRENT, EIT, HASSELAAR, MELIS, PELLO, DENNIS, HUMPHREY, LOUIS
Applicants: SHELL INT RESEARCH, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1994
Main classification: C07C67
IPC codes: B01J31, C07B61, C07C67, C07C69, C08G67